When animals, for instance cows, are milked by machines, vacuum-operated automatic milking systems are predominantly used, wherein with the help of teat cups mounted on the teats of the animals and connected by means of milk tubes to a so-called milk collecting piece, the milk obtained by milking is guided into a central container or into a central conduit. In this milking operation by way of a machine, it is important for the farmer to achieve, on the one hand, a constantly high milk yield and to satisfy, on the other hand, the strict hygienic requirements prescribed by the legislator to the milk producer. Consequently, it is important that the functionality of the automatic milking system provides for both a high degree of wellbeing for the animal to be milked, whereby a high yield is ensured, and a construction which allows for a rapid and efficient cleaning of the system.
An important component of the automatic milking system is the milk collecting piece in which the milk obtained by milking from the individual teats of the animal is collected and then transported into a central conduit. The milk collecting piece is connected by means of flexible milk tubes to the corresponding teat cups and is suspended during milking, due to its own weight, underneath the udder of the animal. Due to the tight mechanical coupling of the milk collecting piece by means of the flexible milk tubes with the udder of the animal, the properties of the milk collecting piece as well as the corresponding connection portions leading to the milk tubes have an effect on the operational characteristics and thus the efficiency of the automatic milking system. Especially during milking and due to the pressure variations generated by the pulsed operation of the milking system, which are required for folding and unfolding the teat rubber in the teat cup, there is a corresponding movement of the milk collecting piece. Depending on the configuration of the milk collecting piece and the milk tubes, a movement of the milk collecting piece can be used in a positive way for stimulating the animal, or the milking operation gets impaired because certain movements are unpleasant for the animal and may thus lead to a premature contraction of the corresponding muscles and thus to a premature end of the milk flow.
A further critical situation arises during the milking operation when a teat cup falls off from the teat or when at the beginning or at the end of the milking operation the teat cups are to be attached to or removed from the teat. Since the milking vacuum is applied to each teat cup and since this vacuum should remain as constant as possible, a removal or a falling off of the teat cup leads to a decline in the milking vacuum, which in turn may lead to a falling off of the remaining teat cups. This also poses problems during removal of the teat cup because not all of the teat cups can normally be removed at the same time so that there is always the risk that the teat cups that are still in the operative position will fall off and thus get soiled. Due to these problems, the milk collecting pieces are designed in many existing milking systems such that the flexible milk tubes which hang downwards due to the weight of the teat cup are kinked in a defined way and thus form an essentially vacuum-tight kink, so that the milking vacuum is hardly impaired on the remaining teat cups.
In a known milking system, the milk collecting piece is designed such that exit openings are provided on the top side of the milk collecting piece for the milk tubes, which thereby leave the milk collecting piece essentially in vertical direction, so that a maximum inner diameter is obtained during operation for the transportation of the milk obtained by milking. Furthermore, a predetermined kink is provided on the milk tube spaced apart from the opening, the kink producing an increased flexibility of the milk tube through a reduced wall thickness of the tube. Furthermore, a kink bracket is provided near the opening so that in the suspended state of teat cups the predetermined kink of the milk tube is positioned above the bracket edge, which ensures a defined kinking and substantially also a sealing of the milk tube. However, the vertical position of the milk tubes in the operative position has the effect during the milking operation that small vertical and also lateral movements of the milk collecting piece, which are e.g. generated by the previously mentioned pressure variations, have a direct effect on the animal's teat. This has the additional effect that even slight positional changes in the milk collecting piece on a specific teat, e.g. during “upward climbing” of the teat cup, have a direct effect on the milk collecting piece and thus indirectly also on the other teats. This may entail a significant negative effect on the animal's wellbeing and thus on the milk output. Furthermore, in said known milking system the kink brackets are mounted very close to the openings receiving the milk tubes, so that during assembly or disassembly of the milk tubes much time and considerable efforts are spent. This has the effect that the willingness to remove the milk tubes for a thorough cleaning process declines considerably.
In a further known milk collecting piece, connection elements are e.g. provided for the milk tubes, the connection elements being arranged in oblique fashion with respect to the longitudinal axis of the milk collecting piece. It should here be noted that in the further description and in the claims the longitudinal axis of a milk collecting piece is defined as an axis coinciding with the vertical if the milk collecting piece is in the operative position and does not perform any movement. The operative position is defined as the position in which the milk collecting piece is fastened by means of the milk tubes and the teat cups to the animal's udder and is suspended vertically downwards due to the dead weight of the whole milking equipment.
Together with correspondingly formed milk tubes, which may e.g. have a portion with a bellows-like structure, the connection elements mounted obliquely relative to the longitudinal axis achieve an attenuating action for lateral movements and also for movements along the longitudinal axis. Said attenuating action is effected by a bending of the milk tubes which is enforced by the oblique arrangement of the connection elements. Furthermore, the end of the connection element simultaneously serves as a kink edge, so that the inner diameter will be deformed significantly when the milk tube, e.g. due to the teat cup's own weight, is pulled downwards. However, it has been found that the milk tube is often not sealed in an absolute and reliable manner because a pronounced predetermined kink is omitted in the tube so that the attenuating action of the tube bend is not impaired during the milking operation. Furthermore, it has turned out that upon kinking of the milk tube said tube partly detaches from the bottom side of the connection element so that milk residues may collect at said place, thereby constituting a potential risk for the hygienic state of the milk. This is particularly the case when during cleaning of the milking system the milk tube is in the unkinked state and the relevant portion on the connection element is thus not cleaned.
Due to the above-illustrated situation, it is an object of the present invention to improve an automatic milking system such that the milking operation can be performed more efficiently, especially when the teat cups are attached or removed and the demands made on hygienic standards can be satisfied more easily.